On Sun, Nov 27, 2011 at 11:09 AM, Wolfgang Denk <w...@denx.de> wrote:
> Dear Tom Rini,
>
> In message
> <ca+m6bxkfrqkzrtipulyn9zi8ztxcyqs+lat4pbkd0nmb3no...@mail.gmail.com> you
> wrote:
>>
>> > Why do we have to permanently disable the data cache just because the
>> > network driver is broken? USB is also broken, and probably other
>> > drivers as well.
>>
>> To be clear, the problem is that today the driver is broken (not cache
>> safe) and this series of patches fixes that problem. In doing so we
>> expose that arm926ejs doesn't have complete cache support today.
>
> But the cahce support works fine for a lot of things - basicly
> everything except for the broken drivers. Why do you want to make ALL
> user suffer from this, even if they don't intend to use the broken
> driver(s) at all?
>
> For example, booting from NAND is probably MUCH faster with caches on.
> Why should we make this slower than necessary?
To encourage someone with the domain knowledge to finish cache support
for the processor?
>> But cache support is incomplete is the problem. None of the flushing
>> operations exist.
>
> Then fix _THAT_.
OK.
>> > It should be sufficient to switch the cache off ("dc off") before
>> > runnign any network related commands (and you want to make sure to
>> > switch it on again afterwards).
>>
>> We can't because we can't compile the driver, once we make it cache
>> safe. It's not today and at least anecdotally the driver doesn't work
>> today on these platforms unless you turn off dcache.
>
> We cannot _compile_ the driver? That's even worse and needs to be
> fixed.
That's what this patch was doing, by disabling the cache so it would
build. To be clear, today it builds but doesn't work with cache on.
>> As a tangent, is pushing new network drivers that aren't cache safe OK
>> if we just say that you need to turn off the dcache before using?
>
> No. We should not accept any such drivers any more.
Noted and as I suspected, thanks.
--
Tom
_______________________________________________
U-Boot mailing list
U-Boot@lists.denx.de
http://lists.denx.de/mailman/listinfo/u-boot
